The present invention related to improvements in protective check-valving, and, in one particular aspect, to novel and improved check valves of uncomplicated low-cost miniaturized construction which respond instantly and automatically to abrupt high surges of fluid pressure by blocking and sealing against the transmission of such pressures to vulnerable structure such as the diaphragm and seals of a capacitance manometer, the improved valves being readily adjustable in response, having self-cleaning characteristics, and operating without externally-applied power.
Fluid valves have of course been long known in many and varied forms, including that of the so-called "check" valve type in which fluid flow is essentially limited to one direction, as by a reciprocatable or hinged valve member, and sometimes involving spring-biasing or electromagnetic actuation. However, when the applications involve such demanding combined requirements as extremely rapid responses, very tight and sustainable valving closures, adjustability of response, instant and positive closures with but minute gaseous flow, and wholly automatic high-speed operation not dependent upon power from an auxiliary source, it becomes necessary to improve upon what has been commonly available. For example, such requirements present themselves in respect of valving which might protect delicate pressure-sensitive devices against sudden large pressure bursts, as in the case of sensitive capacitance manometers whose thin diaphragms and relatively frail seals can be damaged when there is an almost explosive inrush of air upon a breaking open of a very low sensed pressure to a relatively high ambient atmospheric pressure. If injury during such episodes is to be forestalled, the measurement inlet port to such a manometer must be blocked tightly near the very onset of the pressure transient, well in advance of the very brief time it takes the potentially troublesome ambient air pressure to assault the manometer from outside. That allows virtually negligible leeway for detection of abrupt pressure changes and for speedy actuation of valving members in opposition to their inertia. Moreover, the blockage or sealing must be of exceptional quality and integrity, else leakage will prevent the intended protective effects from being realized. Nor is it enough that the blockage be effected and sustained upon sudden increase of the pressure; it must also be possible for the valve to open widely very quickly and thereby allow the associated manometer to perform its intended pressure measurements during processing operations in which there are fluctuations or alternations between high- and low-pressure conditions. Preferably, such valving should be adjustable in response, to serve needs of different processing operations.